1. Field of the Invention
The present invention relates to a driven sprocket fixing structure for motorcycles, and particularly, to a driven sprocket fixing structure for a motorcycle having a cantilever type drive wheel. Note, the term "fixing" as used through this application means securely connecting.
2. Description of Relevant Art
The present applicant has disclosed a rear wheel suspension for motorcycles in Japanese Patent Application Lay-Open Print No. 61-129386, laid open June 16, 1986. The suspension includes a rear swing arm of which a forked front part is vertically swingably pivoted to the vehicle body side. The rear swing arm supports a rear wheel at the rear end thereof, in a cantilever manner. Namely, a rear axle rotatably supported at the central part by the rear swing arm has at both end parts thereof the rear wheel and an annular driven sprocket attached thereto, respectively. The driven sprocket itself is rotatable about the rear axle, and a torque damping mechanism including a plurality of rubber blocks is fixed to the axle, outside the sprocket. Drive power from an engine is transmitted to the driven sprocket, and through the torque damping mechanism to the rear wheel in a slightly elastic manner. The suspension, particularly the torque damping mechanism thereof, permits a smooth transmission of engine torque to the rear wheel even in sudden clutching operation, softening the shock of gear shift, thus achieving a favorable gear shift feeling. The driven sprocket is set on the rear axle, possibly close to the rear swing arm in the transverse direction, so that the bending moment of the axle by the sprocket is minimized.
It however is needed, when removing the driven sprocket from the axle for the inspection or maintenance purpose, to remove also the torque damping mechanism which is installed outside the sprocket. The work is thus relatively complicated.
The present invention has been achieved to effectively solve such a problem in a conventional driven sprocket fixing structure for a motorcycle with a cantilever type drive wheel.